1. Technical Field
The present invention relates to a method of adjusting backlash and a gear mechanism constructed by the backlash adjusting method.
2. Related Art
A balancer has been conventionally known which includes a balance shaft having a driven gear capable of meshing with a driving gear of a crankshaft. A gear ratio of the driving gear to the driven gear is set to, for example, 2:1 in the balancer of this type. Accordingly, the balancer is driven at a rotating speed twice as high as a rotating speed of an engine. This easily causes noise due to backlash, such as rattling noise or meshing noise, and the noise cannot be ignored.
In view of the foregoing noise, for example, a selective fitting procedure is employed for selective assembly of gears. In the selective fitting procedure, gears are selected so that backlash falls within a predetermined dimensional tolerance on the basis of measurement of an over ball diameter (OBD). In this case, however, gears need to be ranked with respect to dimensional tolerance, and the ranked gears need to be prepared as stock. Thus, a problem occurs that stock control is troublesome. Furthermore, since gears belonging to a designated rank need to be selected and assembled, a selection work becomes complicated, resulting in an increase in cost.
On the other hand, for example, gears are coated with resin and can be assembled so that backlash becomes substantially zero with removal of resin coating. In this case, however, since gears need to be coated with resin, a problem also occurs that resin coating increases cost in the same manner as described above.